Merriam-Webster's Collegiate® Dictionary, 11th Edition
JAR
I. verb (jarred; jarring)
Etymology: probably of imitative origin
Date: 1526
intransitive verb
1. to make a harsh or discordant sound, to have a harshly disagreeable or disconcerting effect, to be out of harmony, to undergo severe vibration, transitive verb to cause to jar: as, to affect disagreeably ; unsettle , to make unstable or loose ; shake , jarringly adverb
II. noun
Date: 1537
1. a state or manifestation of discord or conflict, a harsh grating sound,
2. a sudden or unexpected shake, an unsettling shock, an unpleasant break or conflict in rhythm, flow, or transition,
III. noun
Etymology: Middle French jarre, from Old Occitan jarra, from Arabic jarra earthen water vessel
Date: 1592
a widemouthed container made typically of earthenware or glass, as much as a jar will hold, jarful noun
IV. noun see: chare
Date: 1674
the position of being ajar